1. Brief Description of the Prior Art
U.S. Pat. No. 4,494,779, assigned to the assignee of the present invention, describes a terminator connector fitting by which corrugated conduit is connected to an electrical outlet box. The terminator fitting and the corrugated conduit are made of a synthetic resin material, and are characterized by flexibility and limited resiliency. The terminator fitting described in U.S. Pat. No. 4,494,779 is adapted to be forced, as facilitated by the resilient yielding of parts of the fitting, partially through an opening in a side wall of an electrical outlet box. The terminator fitting then snaps into position as the portion of the box defining this opening engages a recess or groove formed in the terminator fitting.
To facilitate insertion of a portion of the terminator fitting into the opening through the wall of the box, the terminator fitting includes a pair of semi-cylindrical collars which can be interconnected, and each of which carries two spaced, box-engaging projections which extend axially from each of the collars and are yieldable radially inwardly sufficiently to permit them to be forced through the opening in the electrical outlet box. The inner side of each of the semi-cylindrical collars is grooved and ribbed to mate with, and engage, corrugations carried on a corrugated conduit to be connected to the electrical outlet box. Each box-engaging projection includes a wedge-shaped free end portion, and also a web portion by which the wedge-shaped free end portion is connected to the respective semi-cylindrical collar upon which it is carried. Each wedge-shaped end portion, associated web portion, and the semi-cylindrical collar to which the respective web portion is connected, define an arcuate channel, groove or relief for receiving and engaging the portion of the wall of the electrical box which surrounds and defines the opening into which the terminator fitting is snapped in assembling the system.
Each of the box-engaging projections is spaced from the adjacent box-engaging projection by a substantial circumferential distance, considered as an arc of a circle, and this spacing serves several functions. First, it requires less material when the terminator fitting is molded of plastic. More importantly, the spacing allows the arcuate dimension of each of the box-engaging projections to be sufficiently small that the respective projection can flex or bend about the web portion by which the respective box-engaging projection is connected to the semi-cylindrical collar upon which it is carried. Further, in providing the circumferential space between adjacent box-engaging projections, each of these projections can flex or bend in a radially inwardly direction as much as is required to permit it to be passed through the generally circular opening in an electrical outlet box. Such opening has a diametric dimension which is less than the outside diameter of the circle which passes through, and includes the largest outside dimension of the several box-engaging arcuate projections when they are collectively considered as a cylindrical array and are in a relaxed, undeflected condition. Without such spacing between the box-engaging projections, they would interfere with each other as they tend to flex radially inwardly, and such radially inward flexure would be limited, in many cases, to an extent such that the terminator fitting could not be forced through the opening in the wall of the electrical outlet box.
Though the necessary freedom of flexing movement is gained in the terminator fitting by providing the described spacing between adjacent box-engaging projections carried on each of the semi-cylindrical collars, it has been found that in the case of some electrical conductor installations where wires are extended through the corrugated conduit engaged by the terminator fitting and into the electrical outlet box, a problem comes to exist as a result of the spacing between the box-engaging projections. This problem is that the portions of the electrical conductors located inside the electrical outlet box, after passing through the corrugated conduit and the terminator fitting, tend to pull back into the space or gap between adjacent box-engaging projections, and to become restricted in their freedom of movement at the free end portions of the electrical conductors and wires. This makes it more difficult to manipulate the conductors as necessary for connection to terminals within the box. Importantly also, on occasion the electrical conductors, after connection within the electrical outlet box, will be pulled into the gap or space between adjacent box-engaging projections of the terminator fitting, and will work against the side edges of one of the projections until the insulation on the conductor is destroyed. Occasionally the conductor is completely severed.
For all of the foregoing reasons, the terminator connector fitting described in U.S. Pat. No. 4,494,779 works well in many installations, and provides a highly useful fitting which can be quickly installed in an electrical outlet box to establish a connection between a corrugated conduit and the box, but such terminator fittings nevertheless do not provide optimum performance in all modes of usage.
2. Brief Description of the Present Invention
This invention provides a terminator fitting of synthetic resin which can be quickly snapped into an opening provided in an electrical outlet box, and there function to retain a corrugated conduit in position relative to the box and the opening so that a system can thus be constructed which more effectively guides and protects electrical conductors used in a system of electrical service. Although the terminator fitting preferably, and most frequently, will be used with an electrical outlet box made of a synthetic resin material, and with a corrugated conduit also made of such material, the terminator fitting can be employed with metallic electrical outlet boxes.
Broadly described, the terminator fitting of the invention preferably includes a pair of semi-cylindrical collars of substantially identical dimension, and which are preferably, but not necessarily, interconnected by a thin hinge strap which can be molded integrally with the semi-cylindrical synthetic resin collars. The collars cooperate, in use, to define, in collective array, a cylinder having a greater outside diameter than the diameter of the opening in the electrical outlet box into which the terminator fitting is to be inserted. In an alternative form of the invention, the two collars may be molded as a single integral unit of cylindrical form.
At the radially inner side of the two semi-cylindrical collars, each collar carries a projection which may, in a preferred embodiment, be in the form of an arcuate rib. The projection is adapted to interfit with and engage the corrugations carried on the exterior of a flexible conduit which is to be connected to the electrical outlet box. As an alternative to such conduit-engaging arcuate ribs, the collars may instead carry yieldable, flexible tongues or tabs, by which engagement with the described corrugated conduit can be effected.
Each one of the semi-cylindrical collars in the pair carries two circumferentially spaced, box-engaging, arcuate projections. These projections extend axially from one end of each of the semi-cylindrical collars. In being molded of a resilient synthetic resin and formed integrally with the collars, the projections are yieldable in a radially inward direction to permit these projections to be displaced by a sufficient amount to be forced through the circular opening in the side wall of an electrical outlet box. Each of the box-engaging projections includes a wedge-shaped free end portion at its terminus spaced from the respective semi-cylindrical collar upon which it is carried, and each projection also includes a hinging web portion by which the wedge-shaped free end portion is connected to the respective semi-cylindrical collar upon which it is carried. Each of the wedge-shaped end portions defines, with the respective semi-cylindrical collar, an arcuate channel, relief or groove extending circumferentially across the respective box-engaging projection. The channel or relief thus defined adjacent the axially inner side of each semi-cylindrical collar is dimensioned for receiving, and relatively snugly engaging, the portion of the wall of the electrical outlet box which surrounds and defines the opening into which the terminator fitting is snapped during the assembly of the system.
The present invention provides as one improvement in a terminator fitting structure, a first blocking flange which is molded integrally to each of one of the two box-engaging projections on each collar at a location adjacent an axial edge thereof. This first blocking flange extends from the respective box-engaging projection upon which it is mounted in a circumferential direction preferably to a point where the free end of the blocking flange lies immediately adjacent an axial edge of the other of the two box-engaging projections carried on the same respective semi-cylindrical collar. Each blocking flange thus substantially fills one of the curcumferential gaps or spaces between the two adjacent box-engaging projections carried on the semi-cylindrical collar. Yet, it is preferably free to flex inwardly as may be needed to allow it to slide beneath one of the box-engaging projections as the terminator fitting is being snapped into the opening into which it is to be received when mounted in the electrical outlet box.
Carried on the second of the two box-engaging projections mounted on the respective semi-cylindrical collar is a second, narrower blocking flange which also has one of its ends molded integrally with, and secured beneath an edge portion of, this second box-engaging projection. This blocking flange also extends circumferentially from the axial edge portion of this second box-engaging projection to a location where it is adjacent the axial edge of one of the box-engaging projections carried on the second or other of the semi-cylindrical collars.
Both semi-cylindrical collars, box-engaging projections and the blocking flanges carried thereon are identically constructed. The second of the semi-cylindrical collars and its respective associated box-engaging projections and blocking flanges is thus described as being constructed in accordance with the description appearing above as characterizing one of the semi-cylindrical collars and its associated pair of projections.
An important advantage of the present invention is that the insulated electrical conductors, which extend through a corrugated conduit engaged by the terminator fitting and into an electrical outlet box in which the fitting is mounted, cannot be pulled back into the gap between adjacent box-engaging projections carried on each of the semi-cylindrical collars, and there be sawed back and forth to destroy the integrity of the insulation on the electrical conductor, or perhaps cause a complete break to occur in the conductor. The spaces between adjacent box-engaging projections are effectively blocked by the blocking flanges which are provided. Yet these flanges are positioned and oriented in such a way with respect to the remainder of the structure that they do not interfere in any way with the inward flexure of the box-engaging projections, which inward flexure is required in order to permit the terminator fitting to be snapped into the opening in the side of the electrical outlet box.
Another important object of the invention is to provide a terminator fitting which is improved in its construction in that it does not interfere with, or cause damage to, electrical conductors passed therethrough and into the interior of an electrical outlet box in which the fitting is mounted.
An additional object of the invention is to provide an improved terminator fitting which can be quickly and easily snapped into an electrical outlet box and concurrently grip and engage a corrugated flexible conduit through which an electrical conductor is to be extended to reach to, and inside of, the electrical outlet box, which terminator fitting is characterized by a long and trouble-free operating life.
Additional objects and advantages will become apparent as the following detailed description of the invention is read in conjunction with the accompanying drawings which illustrated a preferred embodiment of the invention.